Advice on using 50mm 1.8

[Bobby uk]

Just picked up a canon 50mm 1.8 ii and was just asking if there is any advice on best to use it. Its my first prime lens and my first f1.8 and at the mo im leaving it set at 1.8 but im finding that only small parts of my image are sharp! Is there a better af point to use or do i need to just get used to such shallow dof. im using it with a crop sensor and at the mo just for close up portraits. Thanks

 

[WelshNoob]

1.8 as you say is a shallow DOF, it's not that parts of the image are sharp and others aren't, that's what's in focus. Just because it goes to 1.8 it shouldn't be the defacto setting. My tip, try stopping it down more.

 

[dean messenger]

general rule of thumb is for pin tack sharpness 2 stops down on most lenses. so around 2.8 should give you better sharpness while still retaining good DoF.
of course its all down to how far from subject you are too.

 

[Sharky]

If you're focusing and recomposing that could be the issue as the dof is so thin.

To give you an idea of dof f1.8:

1m = 3cm
2m = 11cm
3m = 24cm

http://www.dofmaster.com/dofjs.html

So if you're close while taking a portrait you need to stop down a little which will sharpen up the image and give you a greater dof, step back or choose a different focus point in the viewfinder so you aren't recomposing the shot. Also if you have a body that supports MFA make sure the lens is zero'd to the body so the AF is accurate.

 

[Sharky]

crossposted with rapid keyboard ninja's @dean messenger and @WelshNoob

 

[KIPAX]

using 1.8 ..aim for the eyes

 

[Bobby uk]

Thanks for the quick feed back guys

using 1.8 ..aim for the eyes

True but sometimes a nose an mouth in focus is good to

general rule of thumb is for pin tack sharpness 2 stops down on most lenses. so around 2.8 should give you better sharpness while still retaining good DoF.
of course its all down to how far from subject you are too.

Thanks for that will keep in mind for the next time.

If you're focusing and recomposing that could be the issue as the dof is so thin.

To give you an idea of dof f1.8:

1m = 3cm
2m = 11cm
3m = 24cm

http://www.dofmaster.com/dofjs.html

So if you're close while taking a portrait you need to stop down a little which will sharpen up the image and give you a greater dof, step back or choose a different focus point in the viewfinder so you aren't recomposing the shot. Also if you have a body that supports MFA make sure the lens is zero'd to the body so the AF is accurate.

Again thanks. Is the MFA the micro adjustment. To be honest i have only had the lens a few days so haven't even thought about that yet but will put it on the list.

Am i still correct in saying im better to use the centre af point?

 

[Sharky]

Again thanks. Is the MFA the micro adjustment. To be honest i have only had the lens a few days so haven't even thought about that yet but will put it on the list.

Am i still correct in saying im better to use the centre af point?

Yes MFA = micro focus adjustment, well worth the time and energy if you have it on your body.

Depending on your rough dof using the centre point might or might not work, you'll have to guestimate it. Personally if i know i'm going to be at a very thin dof i'd move the focus point.

All of it depends on what you're shooting, how and the idea of the final image on what you can and can't do.

 

[Bobby uk]

Yes MFA = micro focus adjustment, well worth the time and energy if you have it on your body.

Depending on your rough dof using the centre point might or might not work, you'll have to guestimate it. Personally if i know i'm going to be at a very thin dof i'd move the focus point.

All of it depends on what you're shooting, how and the idea of the final image on what you can and can't do.

Yep i have that and have set my other lens's although they were all spot on. If i get some time tomorrow i will give it a check.
Again thanks for the advice.

" if you don't ask then you don't learn"